<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>首页</title>
</head>

<body>
  <!-- 这个要在端口号是9000里面才行 -->
  <!-- http://127.0.0.1:9000/home -->
  <h1>Nliver</h1>
  <button>点击获取用户数据</button>
</body>
<script>
  const btn = document.querySelector('button');
  btn.onclick = function () {
    const x = new XMLHttpRequest()
    //这里因为是满足同源策略的，所以url可以简写
    x.open('GET', '/data')
    //发送
    x.send()
    x.onreadystatechange = function () {
      if (x.readyState === 4) {
        if (x.status >= 200 && x.status < 300) {
          console.log(x.response);
        }
      }
    }
  }
</script>

</html>